Telephone-exchange system.



Patented Sep1;.3,1912.

4 sums-SHEET 1.

arm y f' i gum/nto@ Wi in emes Patented Sept. 3, 1912.

4 SHEETS-SHEET 2.

ramt

E. E. CLEMENT.

TELEPHONE EXCHANGE SYSTEM.

APPLIoA'rIoN FILED MAR. zo, 190e.

1,037,438. Patented Sept. 3, 1912.

4 SHEETS-SHEET 3.

vwautoz E. E. GLEMBNT. TELEPHONE EXCHANGE SYSTEM.;

APPLICATION FILED MAILZO, 1908.

1,037,438. l w Patented sept. 3,1912.

4 sums-SHEET 4.

SI1/wanton wir emes UNITED STATES- PATENT oEEioE.

EDWARD E. CLEMENT, .OF WASHINGTON, DISTRICT OF COLUMBIA.

Be it knownl that I, EDWARD El CLEMENT', a citizen lof the United States, residing at IVashington, in theV District of Columbia, have invented certain newy and useful Improvements in VTelephone-,Erichang'ev Systems, of which the following is a specification, reference being had therein to t-he accompanying drawing. l l

lMy invention relates to telephone eX- change systems, and especially to those' systems which vemploy automatic switching apj paratus for elfecting connection between subscribers.

i The object of the inventionisto provide` means whereby a calling subscriber whose station is located on a party linemay be connected so as t-o` converse with smother party onjhis own line.

In all automatic systems provision ismade for guarding lines already iii use from interruption, some change in condition of the circuits being relied upon to affect an electromagnet in the testing connector switch, thus giving the equivalent of the operators test in the ordinary manual system. Such a test must extend'to lines which are calling aswell as lines which are called, since a line callingis of course busy for the time being. From this it results that if the line calling is also the line called, then it will find itself busy and be lunable to complete the connection with itself unless special provision is made for a reverting busy test. I make such provision by balanclngpotentials on the test relay when testing back on the calling line only. y

In the present oase a metallic circuit system will bejillustrated' vand f described, in which a ground is placed on the tip side. of

the line oil-.the first trunk duringuse, and the test is made for this ground. If it is` foun/d, the line is busy, otherwise not. In

test-ing, a relay isconnectedA from the test terminal to battery, and in order to accomfplish my present purposes Iprovide that when this test terminal is applied to the tip side of the calling end of the, switching vvcircuit in any particular case, a change is. 'momentarily made on the tip side of the ,answering end of the same by short circuiting theline or by disconr'iecting'onev of' ythebattery supply relays.A Sincethisspecial4 `-condition'only lastsan instant, the chance of thereby letting another party get inA upon the same connection is infinitesimal.,

Specification of Letters Patent.

the finall selection of the lin'e wanted, the

present invent-ion is applicable.

panying drawings wherein: y b F'gures v1 and 2 show two subscribers stations and a portion of the central otIic-e equipment; Fig. 3 shows a rst and second selector switch and a connector switch of the -well known Strowger type; Fig. 4

addition to these I'provide a sending device which is represented diagramm'atically by the" push button O which contains ltwo normally closedcontact springs 0 and o'. The subscriber desiring to send a number, sets down, makes and breaks contact between the springs 0 and o. The line-wires 2 and 3 from the subscribers ,stat-ions terminate in the` central office on the relays S and I. The relay S controls a pair of solenoids A and B, although sluggish relays ycould be used instead.'l The relay I through its armature subscriber at one ofthe stations Ax or AY removes h'isvreo'eiver, from the hook. The

,line 3 is normally lopen to .prevent the estab- 'lishment' ofa false busy-test-circuit through the winding of the relay S.

The-'solenoi'dB Vis connected to the front contacts ofthe relay Sby the wire 24 and to ground by the Wire 29. The solenoid A is connected to the contact s4 and to ground by. the wire 29. The contacts s4, sand s3 are. normally connected and when the relay S' .isr energized and closes the circuit of the solenoid B, battery'is placed on the contact Patented Sept. 3, 1912. IApplicationv ined March 2o, 190s.. seriai 110,422,314.

:My invention is illustrated in the accom-A shows a modified formof part of the central. lstat-ion equipment.

up his sending machine which, when running hook H,'ringers'Q and condenser C. i In closes'l the normally open line 3 when a v s bythe followingI path: battery VB, 22, b',

b, 28,' s?. The solenoid B keeps the -core b` drawn up when the contacts s. and sl ofthe relay S are closed and also the relay' S makes and breaks its contacts during the transmission of the impulses from vthe subscribers station. In other words the core of the solenoid B will only drop down to its normal position after the contacts s and s remain broken for quite a while, as would be thev ,case when a subscriber hangs up -his receiver While this at the end of a conversation. solenoid is active, battery is connected-tothe contact sgof the relay Sand rapid makes and breaks between it and the contact 84. will inl turn keep the solenoid A active allowing the core a5 to remain drawn up so long as impulses are being transmitted.. Between every set of impulses there is a long make or pause caused by 'the subscriber setting up his sending device for transmitting another set of impulses. During this Ainterval the solenoid A is denergized and its core a5 drops down to its normal position. At. the end of the conversation the relay S becoming denergized closes the conta-cts s2 and s* causing the solenoid A tobecome active but at the same time the circuit of the solenoid B is broken at the contacts s and s andv the core b5 thereupon drops,

v'of the solenoid A drops between every group or set of impulses and that the core of. the

solenoid B only drops'at the end vof a con- AverSation. With this combination I am enabled to use the solenoid A forfsending arotary or switching impulse after each set of signals so as to work the side switches in the selector and connector switches. *The solenoid B is used for releasing the various switches. When the core of thissolenoid dropsv down, battery is placed simultaneously on the wires ltand 5 by the closure of the springs b2, b3 and b4. Battery is afterward disconnected from the wires 4v and 5 by the core a5 of the solenoid drop'- ping and opening the contacts a3 `and a.

Bridged battery is connected betweenfthe windings of the relay S and retardation `,coil i I for supplying talking battery to the call-' ing subscriber. The c'ondensers c and c2 are inserted in the wires 3-4 and 2.-.5 respectively to prevent battery iowing to-thev'a- I l y y placf'offthe L.ordinary back release relays `In Fig. 1 when the core of the solenoid A' rions switches.

drops down between each group of impulses in addition to connecting batteryv momen- .tarily to -number 5 side of the trunk, it also connects battery tothe relay S' which upon operating, short circuits or closes together the wires 2 and 3'also the wires 40 and 41 leadingA back to` multiple. contacts in the -connector switches. The test relay J 4, (see Fig. 3), is high 'wound'in comparison with the relay I connected to battery. In automatic exchanges of this type the voltage of -th'e battery is generally-high, from 50 volts In Fig. 2 the operation of therelay S disconnects ,the relay S .from the wires 3 and 40, thereby removing grounded battery connector switches as described in `Letters Patent 815,321 -and 815,176 granted March 13, 1906, to Keith and Erickson. I will not describe these circuits in detail. The first selector switch G has aVveitical relay V` which when energized closes the circuit of the vertical magnet X, which in turn causes 'theV spindle Z, carrying the wipers to step up vertically. 'Ihe rotary relay V' when energized operates the private relay Il, causing the side switches to make one step. The

rotary magnet X has its circuit closed after the side switches have made one movement andwill continue to vibrate, causing the spindle Z to rotate until the test wiper a finds a Contact free from ground. As soon as thishappens the side switches make still another movement, disconnecting the vertical and rotary relays from the trunk wires and" closing the trunk -wires themselves through to the trunk wipers. The last movement of the side switches also connects the trunk release relay J to the test wiper e'.

`The magnet J is the release `magnet and when operated restores the switch'to its normal position.

The circuits of the second selectorswitch G are similar to those of the first selector switch and need not be described. Referring now to the connector switch G2, the

vertical and rotary relays VfL-V5 and vertical and rotary magnets -Xf--X, with-private magn'et U2, control the switch and the circuits Aare generally the same as in the Letters Patent before referred'to, with the exception' of using a relay 'J4 to operate the reelase magnet J 5. lIn this case the relay J 4 is first operated as though it were the release magnet and in turn closes the circuit of the magnet J5. Instead of testing on a `third or 'test wiper, I do the testing directly y onthefvertical or tip side of the line. In

`with the retardation coils I? and I3 with bridged* battery between them for.l supplying current to the-called subscriber'. In this particular case I have shown the contacts 'in the connector switch connected directly to the calling line as I Wish to illustratel and show the method of calling back on the calling line. The change I have made in this circuit does not afl'ect the operation of-this switch in the slightest. The Vvertical relay Vrotary relay V5, private lrelay and the 'ringing relay Y 'remain unchanged and the method of releasing is'the same.

The operation of this system is as follows: Referring to Figs. 1 and 2 the sub` scriber at station AX, desiring to be connected with station AY, on the same line, first removes his receiver which closes the line circuit current flowing .frombattery B, through 22, I, 2,subscribers telephone, o, o', 3, and ground. Thereupon both relays I and S are energized. The pulling up of the armature i of the relay I,I closes the normally open lin'e 3 While the energization of the relay S closes the circuit of the solenoid. B. The core of the solenoid B Anow being drawn up, battery is connected tothe contact s2 of the relay S by the 'following path: batt/ery B, 22, b', b, 23, s2. The relay S at this time being energized, keeps the circuit of the solenoid A open.

vThe subscriber 'at station Ax, after removing his receiver, sets up his sending device to the desired number and this in running down 'makes and breaks the contacts 0 and 0 according to the number of impulses to be sent. These makes and breaks operate the relay S at the cent-ral office which in turn makes and breaks its own contacts. The making and breaking of the contacts .s2 and stcauses the solenoid A to become -energized and draw up the core a5. The mak- A.ing and breaking of the cont-acts s and s keeps the solenoid B energized, while the making and 'breaking of the contacts s2 and s3 sends-impulses over'the trunk Wire number 4c to the first selector switch. These impulses, of course, correspond to t-he makes and breaks of the contacts 0 and o. After this first set of impulses there is a momentary closure of the line l.due to the subscriber setting his sending device for another set of impulses. During this time the relay S remains energized and the core a? of the solenoid A drops down and in doing so momentarily closes together the contactsprings n', a and a2. This closure places batter-y on the trunkwire 5 and changes the kconditions on the line Wire 3. Battery being thusmomentarily placed on the trunk wire 5 operates the rotary relay in the first selector switch, While the change being made on line wire number 3 disables the busy test relayin the connector switch as willlbe de#v scribed later.

Referring now to Fig. 3, the impulses coming over number 4 side of the vtrunk operates the relay V which in turncloses the circuit of the magnet X, which causes the spindle Z to step up vertcallv and first set of bring the Wipers opposite al row of contacts leading to the proper group of secf ond selector switches'. After the first' set of impulses the solenoid A becomes ldeenergized and its core dropping down places battery on number 5 side of the line of the trunk by the following path: battery B, 2v2,

sys, 28, (i2, a', 27, 5.- This impulse operates the relay Vl which Vin'turn closes the circuit of the private' relayU, causing the .side switch. to make one movement, cutting on the rotary magnet X', which causes y the spindle to rotate until the test Wiper finds the contact leading toan idle-second. selector switch. When such a switch is found, the side switch* makes one morev movement, cutting olf the vert-ical and rotary relays and connects the'trunk wires 4 and 5to the trunk Wipers which rest upon contacts leadingV to the second selector switch. The subscriber now being connected to the second selector switch, sends in the second .set of impulses which now operate the second selector switch G lin the same manner that thefirst set of impulses operated the first selector switch. The sub,-

-scriber now being connected to a connector switch ,containing multiples of the desired line, sends in -the'third s et of impulses. This set of impulses coming in operates the relay V, which in turn closes the circuit of the magnet- X, which in turn causes the spindle Z2 to step up vertically and bring the wipers opposite a row containing the contacts leading to the desired line. The rotary impulse now coming in operates the relay V5 causing the side switch to make one. movement, disconnecting 'the magnet X* and in`its placeconnecting the magnet X5; it also connects the test relay J 4 to the tip side of the line through the normally open contacts u and u4 of. the relay U2. The fourth set of impulses now coming in operates the relay V4 which now closes the circuit of the magnet X5, which in turn causes the spindle to rot-ate and bring the wipers to restupon contacts leading to 'the desired line. In this case, the desired line happens to be` the same as the calling line since the Y low resistance shunts vout the testrelay of `relatively high *resistance which is con.

nected to battery, e l

In Fig. 2the test relayfails to find ground as the relay Sis removed-from the extension wirf40, but-is held energized by the .make

followin g path:

` switch to its normal position. 2

before break contacts 82 and 83. The above condition can only be brougl'it about when` trying to signal back on the line tiates the call. It calling for another line and that.y line happens to be busy, ground would be connected to the tip side of the trunk through the relay S or coil I2 and that line would test busy andthe relay 4 would become energized and close the circuit of the magnet J 5 restoring the switch to its normal position. The subscriber now being connected to his own line sets up his sending device so as to send in a. set of ringing impulses. These impulses nowcoming in operate the relay Vt which in turn closes the circuit of the ringing relay Y which became connected when thelast rotary or test impulse was sent in, causing the side switch to make one more movement. These ringing impulses operate the relay Y, erator current von the called line over the generator, 17, 19, 41, 2, Q', 3, and to ground through the relay the end of the conversation the callingfsubscriber upon hanging uphis telephone effects the releaseof the following manner: During conversation the core of the solenoid 'B -remains drawn up while that of the solenoid down. When the calling-subscriber hangs up his telephone the relay S energized, whereupon the solenoid A at .once draws'up its core a5 While the core Zr" 'of the solenoid B beginsto drop, and as soon as it assumes its normal y nected to both sides of the trunk by the following path: battery B, n.4, a, b4, '63, b2, 21, 31. A fter it has assumed its normal position the contacts Z) and b are broken opening circuit of' the solenoid A Whose core o5 thereuponbegins to drop and as soon as it assumes its normal position the contacts a3 and a* are opened and battery is removed from the trunk Wires, 4 and 5 respectively. It will be seen from this method of operation that the joint action ot' these solenoids at the end of theconversation places battery mo-4 mentarily on both sides of the trunk vfor re-y leasing. These momentary impulsesetose the circuit of the relay Vi and the frelayfV'l at the same time, thus closing the circuit of the relay J 4 which in turn closes :the circuit of the magnet J5 restoring .thc...connector of the relay J 2 was closed in series with that of J4 and upon operating closes the circuitof the magnet J 3 restoring the secondselector switch to its normal position. In t-he first selector switch the relay J has its circuit closed in series with themagnet J and becoming energized closes the ,circuit of thegrnagnct. J7.

yrestoring the first selector switchtoitsjnorv mal position. All the apparatus is now rcwhich iniputting gen-- the various switches in A remains becomes defA position battery is con-- used, such as that shown `tion Serial No. 383,875, Afiled July 15th,

'Jhe-'fcircuit inthe second selector switch turned to its normal or. starting position and ready to be used for another call.

In Fig. 4 .I have shown a modified arrangement in which primary selector switches are used to complete the connections of the normally open line-circuits. From the two stations A". and AY extend the line-wires 2 and 3, terminating on the contacts n, n', of the cut-ofrelay N. The line relay M, through the pulling up of its armature m puts current through its individual bank test contact on the actuating Winding of a constantly rotating test vmagnet K. This magnet is provided with an armature having on one end a pin k and on the other end an upwardly extending arm 7a2' adapted to actuate a plug/c3. The magnet'is kept rotating by the engagement of a. pin 7n with a socket in a disk 104 secured on the shaft 705. When however, the test Wiper k6 comes onto the contact k of a calling line, the magnet is energized, the pin c is lifted from its en'- gagement with the disk 7a4, and at the same time the plug k3 is forced outwardly between the co-ntacts la7 and les forcing .them against the contacts 7c thereby completing the .connection of the line circuit with the wires 3 and 2.

-The operation of this primary selector switch has been only brieiiy described since the specific form is not at all essential to the present invention. This switch has been fully described ina prior application. Serial No. 311,388, filed April12, 1906. Any other primary selector switch operating substantially in the same manner may be in a prior applica- The operation of the tip and sleeve relays S*l and In and of the solenoids Aa and Bal is similar to that of their corresponding relays S, A, I, B, in Figs. 1 and 2 and may be readily understood Without going into a detailed explanation, being fully set forth in a previous application, Serial N o. 279,031, filed September 18th, 1905.

AHaving thus described my invention, what I` claim and desire to secure by Letters Patent of the United States is:

1. In a telephone exchange system, a pllrv rality of subscribers lines, means for automatically connecting said lines, 4means for testing a busy line, including a testrelay, and other 4means for shunting said test re,

vlay when the `line calling is .also the line called, thereby preventing the establishment y of a false test circuit. l

'2. In a telephone exchangesystem, a pl11- rality of normally open subscribers? line circuits, means for closing said line circuits when` a liney is calling, automatic switches for connecting said line circuits, means for testing a busy line including a test relay,

other means operating simultaneously for shuntingsaid test relay and rendering it inautomatic switches. v

3. In a telephone exchangesystem, a plurality of normally Open'subscribers linesf means for closing said lines when a station 1s calling, automat-1c swltches for. connecting said lines, a test relay adapted ordinarily to lestablish a testcircuit on a busy line and. 1 a second relay operating simultaneously.

andarranged to short-circuit the test relay Whenthe calling .and the called line are the same, thereby preventing the establishment lof a false. test-circuit.

4. In a telephone-exchange system, a plu-v rality of normally open 'subscribe-rs lines, means actuatedby a calling subscriber for automatically closing' his line, automatic switches Vfor connecting said lines, a test relay adapted under ordinary conditions to ei'ect'the disconnection of the interconnected lines when the called line is busy, a second relay arran edjto short circuit said test relay when t e calling and the called lines are the same, thereby preventing the breakin of the completed connection, and a third re ay arranged to actuate said test and short circuiting relays simultaneously.

5. Ina telephone exchange system, a P111- rality of normally Open subscribers lines,

Ameans actuated by `a calling ,subscriber for automatically closing his line, automatic` switches for connecting said lines, a test relay adapted under Ordinar conditions to effect the vdisconnection O the interconnected lines when the called line is busy, a second relay arranged `tO disable said test relay When-the calling and the called lines are the same, thereby preventing the breaking ofthe completed connection, and a third relay arrangedto actuate said .test and disabling relays. simultaneously.

. In testimony whereof I affix my signature in presence of two Witnesses.

` EDWARD E. CLEMENT. Witnesses: j

L.S. S'rAismar, CHARLES LOWELL HOWARD.

Copies of this patent may be obtained for flve'cents each, by addressing the Commissioner of Patents,

Washington, D: C." 

